Note 11 - Pension Plan and Other Postretirement Benefits - Benefit Payments, Which Reflect Expected Future Service, As Appropriate, Expected to Be Paid Out From Plan Assets (Details) $ in Thousands	Dec. 31, 2019 USD ($)
2020	$ 15,908
2021	16,477
2022	17,116
2023	17,768
2024	18,374
Years 2025-2029	98,994
Executive Survivor and Supplemental Retirement Plan [Member]
2020	1,571
2021	1,681
2022	2,279
2023	2,680
2024	2,627
Years 2025-2029	13,976
Other Postretirement Benefits Plan [Member]
2020	3,323
2021	3,470
2022	3,653
2023	3,720
2024	3,778
Years 2025-2029	$ 19,852

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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